Proposal:Roundabout details

Roundabout details
Proposal status:	Draft (under way)
Proposed by:	Kovposch
Tagging:	roundabout:*=*
Draft started:	2022-08-10

Proposal

Addition to junction=roundabout and highway=mini_roundabout for their layout.

Rationale

• May have different rules (eg lane priority, driver responsibility in crash)
• Provides a simpler initial alternative to setting up type=connectivity, or drawing separate lines in case of raised turbo-roundabout lane dividers. (not a replacement for turn:lanes=* on approach)
• Potentially ease router navigation around more complicates settings (eg very closed spaced pairs)
• Prevents renderers and editors from circularizing shapes that are not circles
• Renderers may cluster roundabout icons more accurately and reliably (?)

TBD: junction=circular

Tagging

Arrangement

• roundabout=*
  • roundabout=single (default)
  • roundabout=double: next to each other, treated as single location
  • roundabout=dumbbell: Separated far enough by usually an overpass/underpass, treated as two locations like a diamond interchange
  • roundabout=turbo: Center island must have cut-out corners in the turbo block concept. Markings only is lane_markings=spiral (see below). (TBD: Any conflicting case of double turbo-roundabout?) May be used together with separation:lanes=*.
  • roundabout=ring: Ring junction / magic roundabout

(TBD: magic roundabout)

• mini_roundabout=*
  • mini_roundabout=single (default)
  • mini_roundabout=double: next to each other. Does not include more widely spaced ones. (TBD: decide on definition)
  • mini_roundabout=ring: Ring junction / magic roundabout

File:Traffic-signs-manual-chapter-5-2004-figure-8x04.svg

Markings

For multi-lane roundabouts.

• lane_markings=* (reused)
  • lane_markings=concentric (default?)
  • lane_markings=partial_concentric https://www.researchgate.net/profile/Ezenwa-Amanamba/publication/303859453/figure/fig2/AS:370912374345730@1465443809880/Concentric-Markings-DfT-1997-B-Partial-concentric-markings-These-also-are-circular.png
  • lane_markings=concentric-spiral https://www.researchgate.net/profile/Ezenwa-Amanamba/publication/303859453/figure/fig3/AS:370912374345731@1465443809909/Partially-concentric-markings-DfT-1997-C-Concentric-Spiral-Alberta-markings-This.png
  • lane_markings=spiral https://www.researchgate.net/profile/Ezenwa-Amanamba/publication/303859453/figure/fig4/AS:370912374345732@1465443809951/Concentric-Spiral-Alberta-markings-DfT-1997-D-Spiral-markings-This-system-is-best.png

When different markings are mixed, split the sections to tag accordingly.

(TA 78/97) CD 116 Appendix D: https://www.standardsforhighways.co.uk/prod/attachments/2b5901c6-3477-4826-b780-cf99003fb5e0

Shape

• roundabout:shape=*
  • roundabout:shape=circle (default)
  • roundabout:shape=oval: Common on single roundabout interchanges, or non-standard junctions.
  • roundabout:shape=dogbone (aka raindrop). Stretched out to both sides, while having only one loop
  • roundabout:shape=square: Only use this if it fits junction=roundabout definition's priority rules

Turning circles and loops

As documented in turning_circle=* and used now. turning_loop=yes can be added to a separately drawn highway=turning_loop . side=* can be added to turning_circle=kunckle and turning_circle=hammer .

• turning_loop=* : Counterpart for shape of highway=turning_loop or the separately drawn highway=* road (some turning_circle=* are likely inapplicable)
  • turning_loop=circle
  • turning_loop=oval
  • turning_loop=square
  • turning_loop=knuckle
  • turning_loop=median : The terminal of a divided road

Comments

Please comment on the discussion page.